This invention pertains to a visual service that employs the full facilities of a television communication channel on an intermittent basis.
The art has provided an auxiliary service in an essentially continuous process that supplies auxiliary information during only a small fraction of the duration of each frame of television subject matter. This typically occurs within the vertical scanning retrace interval.
This service can only occupy a limited area of the television picture, such as a line of printing in the nature of a sub-title.
The art has also provided a single television image frame, or a successive series of frames to provide a pictorial replay from an originating source.
An example is the known stop-motion frame of a football telecast to determine whether or not a touchdown has been made.
A variation of the above is the replay of a hundred to several hundred frames to show an action in the game that is of interest.
These activities occur at the transmitting station under the control of the program director. A choice by an individual viewer as to what he will see is not possible.